[wdmaudiodev] Re: newbie questions

  • From: Tim Roberts <timr@xxxxxxxxx>
  • To: "wdmaudiodev@xxxxxxxxxxxxx" <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Mon, 11 Oct 2010 13:52:05 -0700

Windows XP was released in 2001.  It's not really accurate to call it

> and with any media player available (not just windows media
> player).The audio processing must be controlable for the user and the
> audio processing is intended for music and movie playback
> primarily.How can I do that? From what I have read, it seems I could
> achieve the above by inserting a filter into the audio driver stack. I
> believe this should be possible by implementing an AVStream driver.
> My first question: Is this correct?

In XP, that's really the only option.  In Vista and beyond, you have the
option of implementing a System Effects Audio Processing Object (SysFx
APO), although the philosophy is that such an object is directly
associated with a specific piece of hardware.  The new audio philosophy
simply does not allow your model.   There should not be anything in the
audio stream that the application did not specifically request.  Thus,
you are fighting the system.

> Follow up question? Is there is an easier way to achieve what I want?
> Can it for instance be done without any driver development?

That depends.  If you just want to grab a copy of the final speaker
output, do something with it, and send it somewhere else, you can do
that by using a rendering endpoint in loopback mode.  That won't let you
modify the output stream, but you can monitor it.

Tim Roberts, timr@xxxxxxxxx
Providenza & Boekelheide, Inc.


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